Geiger tube



Sept- 1950 J. A. VlCT OREEN 2,521,315

GEIGER TUBE Filed 001.4, 1947 'INVENTOR.

JOHN A. VICTOREEN Patented Sept. 5, 1950 GEIGER TUBE JohnA. Victoreen,Cleveland, Ohio, ass'ignor to The Victoreen Instrument Company,Cleveland,

Application October 4, 1947, Serial N0. 778,007 I This invention relatesto improvements in tubes for indicating the presence of energizedparticles of radiation, and more particularly to so-called Geiger tubes.

Although heretofore Geiger tubes have been constructed which havefulfilled the limited purpose iorwhich they were intended, with theadvent of advances in nuclear physics and the adaptation of suchknowledge to industrial as Well as medical uses, it becomes moredesirable to provide tubes which are useful other than for merelaboratory application.

Among the disadvantages of the prior tubes was the fact that the lifethereof was limited. Inasmuch as the change in the tube is of a gradualnature, and which may not be recognized by, the commercial user, it isdesirable to provide tubes having a longer life, and wherein thecharacteristics remain fixed over a long period.

Among the things that enter into the use of a tube for commercialapparatus is the geometry of the tube. It is desirable to have certaingeometrical limits maintained in order that the tube will react in apredetermined manner, and in order that tubes may be manufactured havingpredetermined characteristics.

By the present invention I have provided an improved geometry of thetube which permits more stable operation. 1

As is well known to those versed in the art, the tube usually comprisesan outer electrode and a coaxial inner electrodeacross which a potentialis placed. The tube is filled with a noble gas, and the electrodesmaintainedat a potential difference just below the corona dischargepoint. When an energized particle of radiation passes through the wallof the tube, ionization of the gas is efiected causing a current toflow. In order that the current flow thus started is not selfmaintained, a quantity of quenching gas is included in the tube, which,in the absence of the energized particle of radiation, causes theionization to cease and the current flow to stop.

It is by this principle that particles may be counted and thus enablethe user to determine not only the presence of these particles, but thefrequency and quantity. Ordinarily, such particles may include alpha,beta, and gamma rays. Obviously, the type of rays which will energizethe tube may vary to an extent depending on the type of wall used in thetube. As a matter of fact, the tube may also be designed to indicate thepresence of any kind of rays that may be emitted from radio-activematerials and 5 which will penetrate the wall.

8 'Claims. (Cl. 25027.5)

The quenching of the tube is well known and has commonly been effectedby the use of a slight amount of organic vapor such as a' small quantityof ethyl alcohol vapor placed in the tube along with the rare gas. Theuse of the larger gas molecules, such as ethyl alcohol, in a tube ofthis character is accompanied by a gradual destruction of the quenchingvapor which is broken down or disassociated into its components.Eventually, the quenching gas breaks down to such an extent that itbecomes inefiective and/or changes the characteristics of the tube. Thisall pointsto a predetermined limit of tube life and a limitation on thenumber of counts that can be obtained before it must be replaced.Inasmuch as the gas and vapor pressure must be held within criticallimits, this militates against using a larger quantity of liquid or gasin a reservoir because the mere presence of this material in a reservoirwould cause an increase in the vapor pressure and change it so that itmight have undesirable characteristics.

By my present invention,.I provide a tube wherein the destroyed vapor isreplenished. This results in an increased life and enables a tube tomaintain and hold constant characteristics over a longer period of time.

Still other advantages of the invention, and the invention itself, Willbecome more apparent from the following description of an embodimentthereof, which description is illustrated by the accompanying drawingsand forms a part of this invention.

In the drawings:

Fig. l is a diagrammatic view illustrating the geometric relations in atube of my invention.

Fig. 2 is a sectional view of a tube constructed according to myinvention; and r Fig. 3 is a similar view illustrating a modification ofmy invention.

In the drawings, like parts are designated by like reference characters.

As shown in Fig. l, the tube of my invention includes a cylinder [0which may be of glass or other suitable material. An electrode H whichmay be a small diameter wire extends axially into the cylinder, beingbrought in through a press E2. The electrode H terminates spaced fromthe end of the cylinder as indicated at Hi, the end usually beinginsulated by a small glass bead. The interior of the cylinder is coatedwith a conducted material 54, indicated by the shaded area,which coatingstarts at the point !5 and is continued to the end, being connected atits end by a lead l6 which extends through the press I? and is inelectrical contact with the interior coating at the end of the cylinder.If desired, the coating l4 could be replaced by a metal cylinderdisposed inside the tube.

As previously stated, the envelope is, in the main, cylindrical, and thecenter electrode equally spaced from the wall. The ends of the cylinderconform to a portion of a sphere, the radius of which is indicated bythe arrow l8, the axis of which is in the plane of the end of thecoating at the upper end. The other end of the tube is likewisespherical as indicated by the arrow IS, the :axis of the sphere beinglocated at the end l3 of the electrode. It will thus be seen that thecenter electrode is exactly equally spaced at all points from the outerelectrode. A tube is thus provided which is perfectly symmetrical andwith an electrode so placed that its end is on a perfect radius from theouter wall on each end. The tube may be filled with gasand vapor throughthe tubular extensions 20 disposed at either or both ends indicated bythe dotted lines, which tubes are heated and pinched: off after fillingwith gas. This type of construction lends itself to efficientmanufacture with standard tubu-lati'ons and eliminates the need forextra inlet tubes for filling with gas. Having the tubes 20 coaxial withthe rest of the tube also permits a balanced construction whichfacilitates manufacture since it is a balanced construction as the tubesmay be supported at the center on the manifold. It also eliminates theside tube which has a tendency to be broken off easily during use. Theconstruction also permits the tube to be placed in a cylindrical probesince no side tubes are in the way.

In Fig. 2, I have shown another modification of my invention. There isshown the tube wall 13 having the interior coated as indicated by theshaded lines with silver or other material. ends of the tube have sealedtherein in metal tubes 38 and 3| which may be of a material having acoeihcient of expansion similar to that of glass, of which the.so-called Kovar metal is an example. The center electrode l I in thisinstance is supported at. the upper end by a glass bead 32, one end ofwhich extends into the tube 3!. A wire 33 is secured to the other end ofthe bead 32 and extends through the tube 3|. The bottom end of theelectrode H is provided with a helical spring part 34 which extends intothe tube 30. From the spring portion the wire extends through the tube30. The construction lends itself to fabricating the center electrodestructure and allowing it. to be placed in position with the desiredtension thereon. The fabricated electrode is inserted through the twotubes, the upper end is located to provide the desired geometry for theend of the electrode after which a drop of solder is applied to the wireand tube to secure the supporting wire 33 in position and seal the tube.The tube is then conditioned with the desired pressure of gas andquenching vapor which are admitted through the lead tube 35, after whichthe lead tube 35 may be pinched to seal it, as indicated at 35, orsealed by solder at its end.

It will be noted that the tube 3| is provided with a quantity of loosematerial indicated at 31. This is a reservoir of quenching material aswill be more clearly apparent and is held in by a small quantity ofglass wool 38 adjacent the bead 32.

Fig. 3 discloses another modification of my in- The Vided with a coatingof conducting material as indicated by the shade lines. The ends of thetube are provided with glass tubular extensions 40 and 4|. The upperelectrode support in this instance comprises a glass rod 42 which isprovided with a pair of spaced annular flanges 43 and 44'. The lower endof the stem has secured thereto the center electrode I I which isprovided with a helical spring portion disposed in the lower tube H. Theend of the electrode extends out the end of the stem which may be sealedthereto by heating and forming a press 45.

It will be noted that this arrangement likewise lends itself toprefabrication of the center electrode and enables it to be quickly andeasily positioned in the tube. The tube construction lends itself tofabrication from standard tubulations.

The contact for the outer electrode may be made at 53, the leadextending through a tip 5| in which it is sealed and connectedinteriorly to the coating.

A tube 52 may be provided through which the gases may be admitted afterwhich it is sealed off.

The flanges ere-43 cooperate with the: tubular extension as to providean annular chamber around the stem 42. The lower end of this chamber ispacked with a small quantity of glass wool 53. Above the glass wool anddisposed in the chamber isv a quantity of solid material 5'54 which hasthe desired vaporization point. This material may be in a loosegranulated state. or it may be pressed in the form of a slug having acentral opening through which the stem 52 extends. After the material isin position the end of the tube may be heat sealed to the flange 43.

The quenching vapor, as previously stated, may be any one of a number oforganic materials. In order to carry out the replenishing feature of myinvention, I contemplate the use of a solid or granular material havinga vapor pressure which meets equilibrium when enclosed. Such a materialcan be an organic material having a suitable vapor pressure whichprovides the desired quenching. Among those which are suitable arenapthalene crystals, para-di=chlorbenzine and camphor. In the case ofFig. 3, the material can be compressed into the form of a slug and thechamber acts as a porous container which allows the vapor to escape. Ifdesired, the solids could be actually enclosed in a porous containerinside the tube, and as the pressure in the tube is reduced because ofthe disassociation of the gas, the materials will vaporize and maintaina constant partial pressure.

I also contemplate the use of a material which disassociates andreassociates automatically. One such material is ammonia (NHa). Thiswill break down into N and H and will again combine in the presence ofultraviolet rays to again form NHs. There will, therefore, be anequilibrium established in the tube and a substantially continuousdisassociation and reassociation causing a material increase in the lifeof the tube. In their free state the nitrogen and hydrogen have noeffect on the operation of the tube.

I also contemplate the use of a liquid having a vapor pressure, whichliquid is disposed in a reservoir having a chamber wall permeable to thevapor but impermeable to the liquid. Such a material could be water andthe vapor permeable wall cellulose butyrate acetate. Another materialwould be absolute ethyl alcohol and a. chamber wall of gelatin.Regenerated cellulose and so-called nylon could also be used for thewall.

This wall could replace the "glass wool 53 shown in Fig. 3 if desiredand be sealed in the stem 42 and the wall 40.

It will therefore be seen that I have provided a Geiger tubeconstruction which lends itself readily to standard manufacturingprocesses. The tubes, being of a balanced construction, are readilysecured to the standard exhaust manifold for removing the air andfilling with gas. Furthermore, the construction lends itself toproviding tubes which may be held within relatively close limits to astandard. The lack of the side tip of the tubes of Figs. 1 and 2 enablesthem to be readily placed in a cylindrical probe into which they may fitsnugly without the danger of the tips becoming broken or cracked.

In the case of Fig. 2, the Kovar tubing lends itself ideally toservicing the tubes by re-exhausting and refilling should it be desired.

The construction of Fig. 3 assures that the center electrode can besuspended in the same geometric position relative to the outerelectrode, and spring 34 assures that an undue amount of vibration willnot break the electrode or cause it to assume different positions in theenevelope, permitting the tube to be used at any angle withoutmaterially efiecting its operation.

Having thus described my invention, 1 am aware that numerous andextensive departures may be made therefrom without departing from thespirit or scope of my invention.

I claim:

1. A Geiger tube including a container, electrodes in said container, anionizable gas for said container, a reservoir containing an ionizationquenching material, communicating with said container.

2. A Geiger tube including a container, electrodes for said container,an ionizable gas in said container, said container being formed with areservoir and a solid material disposed in said reservoir and comprisinga vaporizable organic material having the characteristic of vaporizingto provide a suitable vapor pressure, said vapor being a quenchingmaterial for said ionizable gas.

3. An apparatus of the class described comprising a substantiallycylindrical container having ends curved on a radius substantially equalto the radius of the tube, an electrode extending axially through oneend of the tube and terminating at the intersection of the radii for theother end.

4. An apparatus for the class described comprising a substantiallycylindrical container having ends curved on a radius substantially equalto the radius of the tube, an electrode extend ing axially through oneend of the tube and terminating at the intersection of the radii for theother end, a conductive coating for said tube.

5. An apparatus of the class described comprising a substantiallycylindrical container having ends curved on a radius substantially equalto the radius of the tube, an electrode extending axially through oneend of the tube and terminating at the intersection of the radii for theother end, a conductive coating for said tube, said conductive coatingextending from the one end of the tube toward the other and terminatingat the end of the tube through which the center electrode extends spacedfrom the end of the tube at the points on the wall of the tube oppositethe point where the radii defining the end of the tube intersect.

6. An apparatus of the class described, a cylindrical glass container, ametallic coating on the inner wall of the container, lead-in tubes onthe ends of the container coaxial therewith, a center electrode, meansto support said electrode comprising a member disposed in one of saidlead-in tubes and extending into the container, said member being formedwith spaced flanges extending close to the Wall of the lead-in tube anda vaporizable organic material disposed in said lead-in tube in thespace between said flanges.

7. An apparatus of the class described comprising a cylindricalcontainer, a conductive coating for said container, lead-in tubesextending into the container from opposite ends axially of thecontainer, a center electrode for said container comprising a supportingwire disposed and sealed in one of said lead-in tubes and having aninsulating bead secured on one end, said electrode being secured in saidbead and extending through said container into the lead-in tube at theother end, a helical spring formed in said electrode at the end disposedin said last mentioned lead-in tube and an extension of said electrodeextending from said spring through said tube and held by said tube.

8. An apparatus of: the class described comprising a cylindricalcontainer, a conductive coating for said container, metallic lead-intubes extending into the. container from opposite ends axially of thecontainer, a center electrode for said container comprising a supportingwire disposed and sealed in one of said lead-in tubes and having aninsulating bead secured on one end thereof, said electrode being securedin said bead and extending through said container into the lead-in tubeat the other end, a helical spring formed in said electrode at the enddisposed in said last mentioned lead-in tube and an extensionoi saidelectrode extending from said spring through said tube and held by saidtube.

JOHN A. VICTOREEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,122,222 Vingerhoets June 28,1938 FOREIGN PATENTS Number v Country Date 87,583 Austria Mar. 10, 1922296,769 Great Britain Apr. 25, 1929 472,110 Germany Feb. 22, 1929 OTHERREFERENCES .Korif: Electron and Nuclear Counters; D. Van Nostrand Co.,New York, Apr. 1946, pp. 97-100 and 129.

Strong: Procedures in Experimental Physics: Prentice-Hall Inc., NewYork, page 261.

Korfi: Electron and Nuclear Counters; D. Van Nostrand Co., Inc., NewYork, pp. 124-128.

